Collect the Collection of Souls.
<The blood drains out of Toshley's face.>
These orbs are made up of both nether energy and souls, some of them gnome souls!
How dare they! Were they the ones killing our people that traveled north?!
<name>, you must put a stop to this, and the only way to do that is to finish off their leader, Nexus-Prince Razaan.
You'll have to coax him out of hiding though. I'm guessing that you can do that by killing a lot of his Razaani ethereal.
Bring me the collection of souls that he no doubt has.